In recent years, a virtual machine system has been used in an increasing number of information devices, such as tablet devices, that deal with confidential information (see Patent Literature 1). Confidential information is information that is permitted to be used under certain conditions. One example of the confidential information is images of users, or emails.
In a virtual machine system, a user application such as an image viewer or a mailer that deals with confidential information is operated in one virtual machine to realize a function such as image display or email transmission/reception. The one virtual machine restricts use of the confidential information to a user himself/herself by causing the user application to perform a user authentication and permitting use of the confidential information only when the user authentication results in success.